Curable, or thermosettable, coating compositions are widely used in the coatings art, particularly for topcoats in the automotive and industrial coatings industry. Basecoat-clearcoat composite coatings are particularly useful as topcoats for which exceptional gloss, depth of color, distinctness of image, or special metallic effects are desired. The automotive industry has made extensive use of these coatings for automotive body panels. Automotive clearcoats must meet many performance requirements. They must be smooth and glossy to provide the desired aesthetic appeal. They must also be durable, both to preserve the coating appearance and to protect the steel substrate, by resisting scratching and marring and also degradation from UV light in sunlight, environmental etching, and heat.
Carbamate-functional materials have found particular utility in coating compositions as cross-linkable resins. Clearcoat compositions containing carbamate-functional acrylic polymers can provide significant advantages over other coating compositions, such as hydroxy-functional acrylic/melamine coating compositions as a solution to the problem of environmental etch. Environmental etch, or acid etch, results in spots or marks on or in the coating that often cannot be rubbed out.
While such polymers and compositions containing carbamate-functional materials provide a significant improvement over the prior art, improvements in some areas are still desirable. In particular, it would be advantageous to provide polymers exhibiting the ability to go over solvent-borne as well as water-borne basecoat paints, while still possessing the positive environmental etch and performance characteristics of carbamate-functional acrylics.
Thus, there remains a need for coating compositions that have both solvent-borne and water-borne capabilities and can be applied using existing equipment in plants that are configured to handle more traditional coatings technology. Such a coating composition still must provide a cured coating having the desired physical properties.